you can easily rearrange them by dragging and dropping them from/to where you want them on the dropdown bookmark menu.....
Since you seem knowledgeable about Firefox...
The old (some months ago) mozilla firefox browser would bring up my most recent-visited web addresses when I clicked on the arrow at the end of the address bar.
But now the same addresses appear every time -— they never change, even if I go to other web sites. How do I get it back to where it will bring up my most recent addresses?
I loved that feature, very convenient. Thanks for any help.